Dimensional stabilization of cellulose materials



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sss stz Patented Apr. 2, 1963 3,084,972 DfiidENSlGlJAL STAEELEZATEQN F ELLULSE MATERKALS Stanton E. Deeley, Kearny, Ni, assignor to Jacques Wolf $1 (10., Newark, Null, a corporation of New Jersey No Drawing. Filed Dec. 27, 19%), Ser. No. 73,215

11 Claims. (Cl. 117144) This invention relates to an improved process for achievement of dimensional stabilization of cuprammonium rayon and other cellulose fiber and fabric materials.

Rayon is a highly desirable fiber for use in the textile industry because of its ability to be spun into filaments ionger and finer than silk and most other fibers. It also has excellent dye qualities due to the large number of active hydroxy groups on the polymer enabling it to be ionically bonded to various dyestuffs. It is dyeable by the normal vat and direct dye processes used in the dye industry. However, in the textile industry the use of cupr-ammonium rayon and other cellulose fiber materials has been seriously limited by the severe effect which humidity has on the dimensional stability of these materials. Changes in humidity cause the fibers to shrink or to elongate. This phenomenon is visually noticeable and very undesirable in such articles as drapes, rugs, suit linings and labels made from such fibers and it has seriously limited the usage of these fibers.

Previously in the art, fiameproofing agents such as tetralcis (hydroxy methyl) phosphonium chloride, hereinafter referred to as THPC, have been bonded to these regenerated fabrics and fibers by means of urea formaldehyde resins and melamine formaldehyde resins. The function of these resins was to give the fabrics and fibers dimensional stabilization as well as flame retardant properties. When the formaldehyde resins and the THPC were applied together onto the fiber, the THPC was actually held onto the fiber by the formaldehyde resins. The impregnation of the fabric with the THPC and the formaldehyde resins is carried out in conventional fabric treating equipment, for example, by dipping the fabric or fiber in a solution of the resins and THPC and then passing the impregnated fabric through quetch rolls to remove excess solution, or by impregnating the fabric or fiber in a padder. The wet impregnated fabric is then subjected to heat treatment and aeration to further polymerize the resins. However, the use of these solutions brought about poor hand in fabrics and fibers treated with same. That is, the formaldehyde-THPC compositions which were necessary to stabilize these materials tended to give the materials a very stiff hand in comparison to the untreated fabrics and fibers. Hence since the hand of the fiber and fabric is very important in the garment and drapery industry, this treatment is of limited value.

Epoxy resins have been used in attempts to give these fibers dimensional stability but here again a fabric and fiber material resulted which also had a poor hand due to the stiffness of resulting treated materials.

Attempts have also been made by padding solutions of IHPC on the fiber, squeezing out the excess and then curing the THPC onto the fiber by heat, aeration and ageing. The amount of THPC added onto the fiber by this method was approximately to 15 percent based on the weight of the fiber material so treated. The curing of the THPC onto the fiber consumed considerable time and required many steps and the THPC was not afiixed firmly enough to the material to withstand removal by repeated washing.

U.S. Patent No. 2,911,325, Drake et al., issued November 3, 1959, discloses the achievement of dimensional stabilization and fiameproofing of rayon by reacting an aziridinyl compound with a methylol phosphorus compound to form a fiame-retardant polymeric reaction product which may be deposited on the surf-aces of rayon fibers. The degree of adhesion of the polymeric reaction product onto the fibers so treated is not suificient to permit repeated laundering of the fabric without loss of some of the reaction product from the fibers so treated. Moreover, the process of US. Patent No. 2,911,325 relies on large excesses of the aziridinyl compound and the methylol phosphorous compound in the treating bath thus rendering the process very costly.

It is anobject of this invention to provide a method of dimensionally stabilizing cuprammonium rayon and other cellulose fibers without seriously affecting the hand of the fabric and fiber.

It is a further object of this invention to provide an economical method to disperse, aflix and polymerize THPC onto cuprammonium rayon and other cellulose fibers.

Other objects of this invention will in part be obvious and will in part appear hereinafter.

In accordance with my invention, it has been discovered that cuprammonium rayon and other cellulose fiber and fabric material can be dimensionally stabilized by bonding polymerize-d THPC onto the material. This is accomplished by immersing the material in a solution of neutralized THPC and dispersing the THPC onto the material. The THPC which has been dispersed onto the material is then polymerized and bonded onto the material by contacting the material throughout with ammonia while maintaining the pH of the bath between about 7.2 and 7.5. Thereafter the material can be cured and any excess chemicals can be removed. Fiber and fabric materials so treated no longer exhibit their usual dimensional instability in the presence of water and water vapor.

The THPC used in my invention is commercially available. It is obtained in about percent yields based upon the formaldehyde or the hydrochloric acid used in its preparation by reacting phosphine with formaldehyde and hydrochloric acid at room temperature. It is a crystalline compound that is soluble in water and lower aliphatic alcohols, but insoluble in most other organic solvents.

The amount of THPC required to be dispersed and bonded onto rayon and other cellulosic fiber and fabric materials in order to dimensionally stabilize such materials is approximately 5 to 10 percent based on the weight of the material to be treated. Lesser amounts of THPC may be added to the material but to assure complete dimensional stability it is preferable to add between about 5 and 10 percent of THPC based on the weight of the material to be treated.

The practice of my process is very straight-forward. The fabric or fiber material to be dimensionally stabilized is placed in a bath or vat such as a dyebeck containing water or some other suitable solvent for the TI-IPC which will permit complete dispersion of the THPC onto the material to be treated. The amount of solvent required in the bath should be such that the THPC may be adequately dispersed onto the fiber. It has been found that the bath operates efficiently when the weight ratio of fiber solvent to fiber is between about 10:1 and 30:1,

although the liquid to fiber ratio is not critical other than that enough solvent should be present to permit adequate dispersion of the THPC onto the materials to be treated. In the preferred embodiment of my invention I use a liquor to fiber ratio of about 20:1 based upon their re spective weights.

Inert solvents such as water and lower aliphatic alcohols such as ethyl alcohol, methyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and mixtures of these alcohols with each other and with water have been found useful as solvents for my invention. In the preferred embodiment of my invention I use water as the solvent. However any inert solvent which will permit adequate dispersion of the THPC onto the material being treated may be used. f

The THPC is neutralized with a base prior to addition to the bath. Neutralization is carried out in order to reduce the solubility of the THPC in the bath thereby assuring adequate dispersion upon the fiber. Any base or mixture of bases may be used to neutralize the THPC that will not polymerize and thus precipitate the THPC directly out of the bath. Bases which directly polymerize the THPC in the dyebath causing the THPC to precipitate out directly in the dyebath are those bases which contain a free ammonia group such as ammonium hydroxide. Illustrative of bases that may be used to new tralize the THPC are aliphatic alkanol amines such as triethanolamine, diethanol amine, monethanol amine, hexanol amine, cyclohexanol amine. Preferably triethanolamine is used to neutralize the THPC. Inorganic bases such as sodium hydroxide, may be used to neutralize the THPC. However, due to the strong basicity of inorganic bases, neutralization with these bases is difiicult.

The neutralized THPC, the solvent and the material to be treated are brought together in the bath which optionally can be agitated, e.g., for approximately 15 minutes, to permit the THPC to disperse and afiix itself evenly on the material. The material being treated can be visually checked by the operator to assure that the THPC is uniformly dispersed and afiixed thereon. When adequate dispersion and affixation of the THPC onto the material is accomplished, the material will have a slightly uniform swollen appearance.

The next step of my invention is to contact with ammonia the material upon which the neutralized THPC has been dispersed. This treatment is carried out in order to polymerize the THPC which has been dispersed upon the material. The treatment with ammonia will also disperse and aflix onto the material any THPC remaining in the treatment bath. The ammonia may be supplied to the bath directly from a 'tank of ammonia or it may be formed, e.g., liberated, directly in the bath as a result of chemical reaction 'betweenan ammonia-containing compound (ammoniumsaltcompound) and a base. However, the pH of the bath during the treatment with ammonia must be maintained between 7.2 and 7.5. If the pH of the treatment bath is allowed to rise above 7.5, the THPC present in the bath will polymerize too rapid- "ly and precipitate directly into the bath. If the pH of the treatment bath is allowed to fall below 7.2, the THPC cannot 'be polymerized. If gaseous ammonia is used to treat the material, the pH of the bath can be maintained within the limits given above by regulating the rate at which the ammonia is liberated in the bath.

Although as indicated above, the ammonia utilized to polymerize the THPC may be supplied directly into the dyebath from a tank of 'pure ammonia gas, it has been found that it is extremely diflicult to regulate and maintain the pH of the bath between 7.2 and 7.5 when such an ammonia source is used. Preferably,'sufiicient ammonia is supplied at a proper 'rate throughout the treatment bath by adding a quantity of an ammoniacontaining compound to the bath and reacting the ammonia-containing compound with abasic bufiering agent, thus liberating ammonia. This method of supplying ammonia also permits a facile method of maintaining the treatmentbath at a pH from between 7 .2 and'7.5. However, my invention is notto be limited by the means -chosen to supply the ammonia since any means which will supply ammonia throughout the treatment bath may be used provided the pH of the bath is maintained at a pH between 7.2 and 7.5.

once at the beginning of the ammonia treatment or incrementally as it is needed during the treatment to supply ammonia. However, in the preferred embodiment of my invention the ammonium salt compound is added all at once at the beginning of the ammonia treatment because I have found that the presence of the salt in the bath increases the substantivity of the THPC for the material being treated. Ammonia is supplied throughout the bath until all of the THPC present in the bath is adequately afiixed and polymerized onto the material being treated. A simple test to determine when the THPC is sufficiently dispersed and polymerized on the fiber can be performed by the operator. A sample of the bath solution is removed and a small amount of ammonium hydroxide is added to this sample solution. If the solution remains free of a fiocculent precipitate, sufficient ammonia has been supplied throughout the bath. The presence of a fiocculent precipitate in the sample indicates that further ammonia must be supplied by the bath in order to completely disperse and polymerize the THPC onto the material being treated. The proper rate of liberation of ammonia is easily determined by the maintenance of the pH of the bath between 7.2 and 7.5.

After sufiicient ammonia has been supplied throughout the bath as determined above, preferably between 1 and 5 percent of concentrated ammonium hydroxide based upon the weight of the material being treated can be added to thebath to assure complete polymerization of the THPC on the material being treated.

The fiber or fabric material so treated is then removed from the bath to a hot-air oven where it is dried at a temperature ranging from between about 240 F. and 275 'F. If additional curing of the THPC is necessary or desirable, the fabric and fiber material may then be cured for about 5 minutes, at a temperature of about 280 F. After the fiber or fabric material has been dried and optionally cured, the material may then be scoured by conventional means used in textile houses to remove any excess treatment chemicals.

Ammonium compounds that may be used to supply ammonia to disperse and polymerize the THPC onto the material are those ammonia containing compounds that do not raise the pH of the bath above about 7.5 when added to the bath or when they are reacted with the'basic buffering agent. The ammonium compound when reacted-with the buffering agent should liberate a slow steady stream of ammonia which will permit adequate deposition and polymerization of the THPC ontothe fiber. The 1ammonium salts of organic and inorganic acids and hydroxyl amines have been found to fulfill the requisite of "ammoniumsalt compounds used in this invention for the liberation .of ammonia when reacting with the buffer materials.

Ammonium chloride, ammonium sulfate, ammonium phosphate, hydroxyl amine and ammonium acetate are illustrative of ammonium compounds that may be utilized in this invention and reacted with the buffering agent to liberate ammonia properly. The amount of the am- .monium compound which can be added to the bath varies from about ,2 to 12 percent based on the weight of the fiber and fabric material to be treated. Overaddition of :the ammonium compound will not harm the material being treated nor will it excessively polymerize the THPC onto the fiber and fabric but it does not produce any bene- .ficia1 results. However, underaddition of .the ammonium .compounds will cause insufficient aifixation andpolymerization of the THPC onto the material being treated.

The buffering agents usable in my invention are those materials which are soluble in the solvent used in the treating bath and which will react with the ammonia-containing compounds to provide a slow steady liberation -of ammonia 'througho'utthe bath. They also must be able to maintain the'pH of the bath between 7.2 and 7.5. The di basic, tri basic and tetra basic salts of sodium phosphate and potassium phosphate are given as illustrations of buffering agents that are usable in my invention. The methods outlined above are merely given as illustrations of methods that may be used to liberate a slow steady stream of ammonia throughout the treatment bath. Any method which will liberate ammonia throughout the bath while maintaining the pH of the bath, between 7.2 and 7.5 may be utilized in my invention. In the preferred embodiment of my invention ammonium chloride is reacted with tetrasodium pyrophosphate in the treating solution to yield ammonia.

The temperature of the bath is not a governing factor of my invention and the reaction may be carried out at room temperatures or at elevated temperatures. In the preferred embodiment of my invention all of the components are admixed at room temperatures and during the liberation of ammonia throughout the bath the temperature of the bath is raised slowly until it reaches 190 F.

The fabrics treated by my invention may be dyed in any conventional manner before or after being treated by the THPC as described herein. The addition of THPC to rayon by my process causes no noticeable change in the hand of the treated fabric and fiber materials. The fiber and fabric materials so treated may be washed or drycleaned without any loss of the THPC which has been added to the material. Cellulose fiber and fabric materials that are dimensionally stabilized by my invention are regenerated cellulose materials such as cuprammonium rayon and viscose rayon and natural cellulose materials such as cotton and flax. These cellulosic materials can be treated by my process in the form of fibers, filaments or yarns as well as in the form of woven and nonwoven fabrics.

My process provides a cheap and easily operable method of dimensionally stabilizing cellulose materials, especially rayon, against the effects of water and steam or humidity. it is surprising that my novel process exhibits such outstanding results since several of the compounds which I use in my process have been used heretofore in dimensional stabilization without exhibiting the combination of outstanding properties which I have been able to achieve. For a fuller understanding of the nature and objects of my invention reference should be had to the following examples which are given merely as further illustrations of the invention and are not to be construed in a limited sense.

Example I In this example, four strips of a low denier Bemberg cuprammonium rayon material, each strip measuring 14 feet by 4 inches and weighing 60 grams, were scoured with a scouring composition containing 0.25 gram of sodium dodecyl benzene sulfonate, 0.5 gram of the condensate of octyl phenol and 8 mols of ethylene oxide and 5,000 grams of water at 150 F. for /2 hour in a dyebeck. One strip of the material was removed and rinsed in warm water to remove any residual scouring agent and was dried and ironed fiat. This sample was labeled Control #1. The other strips of material were dyed by immersing them in a solution containing 4 grams of solophenyl brown dye, 50 grams of sodium chloride and 4,000 grams of water at 190 F. One of these dyed strips of material was removed, rinsed in warm water to remove any excess dye and scouring agent, dried and ironed fiat. This strip of material was labeled control #2. A third strip of material was removed, put aside and allowed to remain wet. This strip of material was labeled control #3. The remaining strip of material was then placed in a treatment bath containing 1,200 grams of water. Six grams of THPC which had previously been neutralized with 2.5 grams of triethanol amine were added to the bath. The strip of material in the bath was then agitated for minutes, at which time it was noted that the strip of material had a slightly uniform swollen look. Five grams of ammonium chloride were added to the bath along with sufiicient amounts of tetra sodium pyrophosphate to raise the pH of the bath to 7.5. The temperature of the bath was then gradually raised to 190 F. The pH of the bath was constantly checked and as it dropped to 7.2, further additions of tetra sodium pyrophosphate were made to keep the bath at a pH of 7.5. When no further decreases in the pH were noted, 6 grams of ammonium hydroxide were added to the bath and the strip of material was removed and dried in an oven at 240 F. When the strip of material was dry, it was cured for 5 minutes in an oven at a temperature of 280 F. It was then washed to remove excess treating chemicals and labeled strip #4. The wet control strip #3 was treated in the same manner as strip #4 except that THPC was not added to the bath. Both control strip #3 and strip #4 were washed and ironed flat. There Was no noticeable difference in the hand or color of any of the dyed strips so treated when compared with the untreated strips.

All four strips were then hung up vertically lengthwise in order to observe the effect of humidity on their dimensional stability. The following chart reproduces the observations which were carried out over a period of one week. The values given in the chart indicate the increase or decrease in length of the various strips at varying humidities over their original length of 14 feet.

23% 50% Sample Relative Relative Relative Humidity Humidity Humidity No change ineh +1 inch.

lnch inoh +154 11011. inch inch inch. Strip N 0 change No change" No change.

The above clearly illustrates the effectiveness of my process for afiixing and polymerizing THPC onto regenerated cellulose materials to dimensionally stabilize these materials against changes of relative humidity. It further illustrates that the material can be dyed prior to treatment by my process without any harmful effects occurring to the color or hand of the material. It shows that materials so treated can be used in the textile industry without regard to the original dimensional instability of such materials.

Example 11 In this example, 100 pounds of cuprammonium rayon fiber and 2,000 pounds of water were placed in a large vat. 6 pounds of THPC previously neutralized with 2.5 pounds of triethanol amine were added to the vat and the vat then agitated for 15 minutes. Six pounds of ammonium chloride were added to the bath along with suificient tetrasodium pyrophosphate to raise the pH of the bath to 7.5. The temperature of the bath was then gradually raised to F. The pH of the bath was constantly checked and as it dropped to 7.2, further additions of tetra sodium pyrophosphate were made to maintain the pH of the bath at 7.5. When no further decreases in pH were noted, the fiber was removed to a hot air oven and dried at 240 F. The fiber was then scoured to remove excess treating chemicals. The fiber so treated exhibited the same hand qualities as the untreated fibers. This example illustrates that the fibers may be dimensionally stabilized prior to being woven into fabrics without any damage occuring to the hand of the fiber.

Having described my invention, What I claim as new and desire to secure by Letters Patent is:

l. A process for dimensionally stabilizing cellulose fiber and fabric material which comprises polymerizing and bonding tetrakis (hydroxy methyl) phosphonium chloride onto said material in one step by immersing said material in an inert solvent containing neutralized tetrakis (hydroxy methyl) phosphonum chloride and contacting said material throughout while immersed in said solution with ammonia while maintaining the pH of said solution between 7.2 and 7.5 until all of said tetrakis (hydroxy methyl) phosphonium chloride has been dispersed onto and bonded to said material, thereafter removing said material from said bath and drying said material, there being present in said solvent at least about of tetrakis (hydroxy methyl) phosphonium chloride based on weight of-said material.

2. The process of claim 1, wherein said solvent contains a solvent-material weight ratio varying from about 10:1 to about 30:1.

3. The process of claim 1, wherein said solvent contains from about 5 percent to about 10 percent of tetrakis (hy.droxy methyl) phosphonium chloride based on the weight of said material.

' 4. The process of claim 1, wherein said material is cuprammonium rayon.

5. The process of claim 1, wherein said material is viscose rayon.

6. The process of claim 1, wherein said material is cotton.

7. The process of claim 1, wherein said tetrakis (hydroxy methyl) phosphonium chloride is neutralized by trlethanol amine.

8. The process of claim 1, wherein said ammonia is obtained by reacting an ammonium compound with a basic buffering agent.

9. The process of claim 8, wherein said ammonium compound is ammonium chloride.

10. A dimensionally stabilized eellulosic fiber and fabric material produced by the process of claim -1.

11. A process for dimen fonally stabilizing cellulose fiber and fabric materials which comprises; polymerizing and bonding tetrakis (hydroxy methyl) phosphonium chloride onto said material in one step by immersing said material into a solution of neutralized tetrakis (hydroxy methyl) phosphonium chloride, said solution containing from about 5 percent to about 10 percent of tetrakis (hydroxy methyl) phosphonium chloride based on weight of Said material, said tetrakis (hydroxy methyl) phosphonium chloride having been previously neutralized by triethanol amine, said sol tion containing about 20 parts by Weight of Water for each part by weight of said material simultaneously contacting said material immersed in said solution with ammonia while maintaining the pH of said solution between 7.2 and 7.5 until all of said tetrakis ,(hydroxymethyl) phosphonium chloride has been dispersed onto and bonded to said material, said ammonia being formed by reacting ammonium chloride and tetrasodium pyrophosphate in said solution and raising the temperature of said solution to about F. while said material is being contacted by said ammonia; thereafter removing said 'material from said solution, drying said material about 240 F., curing said dried material at about 280 F. for about 5 minutes and scouring said dried and cured material.

References Cited in the file of this patent UNITED [STATES PATENTS 

1. A PROCESS FOR DIMENSIONALLY STABILIZING CELLULOSE FIBER AND FABRIC MATERIAL WHICH COMPRISES POLYMERIZING AND BONDING TETRAKIS (HYDROXY METHYL) PHOSPHONIUM CHLORIDE ONTO SAID MATERIAL IN ONE STEP BY IMMERSING SAID MATETRIAL IN AN INERT SOLVENT CONTAINING NEUTRALIZED TETRAKIS (HYDROXY METHYL) PHOSPHONUM CHLORIDE AND CONTACTING SAID MATERIAL THROUGHOUT WHILE IMMERSED IN SAID SOLUTION WITH AMMONIA WHILE MAINTAINING THE PH OF SAID SOLUTION BETWEEN 7.2 AND 7.5 UNTIL ALL OF SAID TETRAKIS (HYDROXY METHYL) PHOSPHONIUM CHLORIDE HAS BEEN DISPERSED ONTO AND BONDED TO SAID MATERIAL, THEREAFTER REMOVING SAID MATERIAL FROM SAID BATH AND DRYING SAID MATERIAL, THERE BEING PRESENT IN SAID SOLVENT AT LEAST ABOUT 5% OF TETRAKIS (HYDROXY METHYL) PHOSPHONIUM CHLORIDE BASED ON WEIGHT OF SAID MATERIAL. 